To prevent guillotine from double leg, couple options, the head in the middle works (also you can kind of headbutt them in the solar plexus ) or if your head is outside, have your head on their hip bone area, chin tucked, outside shoulder raised.

If you do get caught, make sure to keep your hips raised, shoulder pressure right on their neck, and thats a good way to aleviate a lot of the strain from a guillotine and get out of it.

As far as from the shot, youll get the feel of a proper takedown, but if you keep your hear on their hip, chin turned into your opponent, thats a safe bet, if they try to sinch of hte guillotine, its not really gonna be there and theyll waste energy.